extraction in orthodontics references:orthodontics at a glance,contemporary orthodontics,introduction to orthodontics

1. Extraction in orthodontics
Mustapha assad mohammed
&
Muna shehab ahmed

2. Extractions
• Before planning the extraction of any permanent teeth it is important to ensure that all
remaining teeth are present and developing in a satisfactory position. The factors governing
the choice of teeth for extraction include the following:
1) Prognosis.
2) Position.
3) Amount of space required and where. Provided that relief of crowding only is indicated, the
following is a general guide: 1–2 mm per quadrant, first pre-molar extractions should be
avoided and a specialist opinion sought; 3–5 mm per quadrant, often indicates premolar
extractions; more than 5 mm per quadrant, extractions and space maintenance, or even the
extraction of more than one tooth per quadrant, may be necessary.
4) The incisor relationship.
5) Anchorage requirements and desired buccal segment relationship at the end of treatment.
6) Appliances to be used.
7) Patient's profile.

3. • If extractions are required in both arches, forward movement of the
buccal segments to close space spontaneously will be facilitated if
the same tooth is removed in both the maxilla and the mandible
• The position of the tooth being extracted within the arch will affect
the anchorage balance between the teeth anterior and posterior to
the extraction site. This means that extraction of first premolars will
give greater space for alignment and/or retraction of the incisors
than extraction of second pre-molars, which in turn provides more
space than extraction of first molars, and so on.

4. In patients with excessive
incisor protrusion, retracting
the incisors improves facial
esthetics. This young woman
sought treatment because of
dissatisfaction with the
appearance of her teeth.
After orthodontic treatment
with premolar extraction and
incisor retraction, dental and
facial appearance were
significantly improved. A and
B, Appearance on smile before
and after treatment. C and D,

5. Contemporary Extraction Guidelines
• Less than 4 mm arch length discrepancy:
1. Extraction rarely indicated (only if there is severe incisor protrusion).
2. In some cases, this amount of crowding can be managed without arch expansion
by slightly reducing the width of selected teeth, being careful to coordinate the
amount of reduction in the upper and lower arch.
• Arch length discrepancy 5 to 9 mm:
1. Nonextraction or extraction treatment possible.
2. The decision depends on both the hard- and soft-tissue characteristics of the
patient and on how the final position of the incisors will be controlled; any of
several different teeth could be chosen for extraction. Nonextraction treatment
usually requires transverse expansion across the molars and premolars, and
additional treatment time if the posterior teeth are to be moved distally, to
increase arch length.

6. Contemporary Extraction Guidelines
•Arch length discrepancy 10 mm or more:
Extraction almost always required.
For these patients, the amount of crowding virtually equals the amount of
tooth mass being removed, and there would be little or no effect on lip support
and facial appearance.
The extraction choice is:
1. four first premolars
2. or perhaps upper first premolars and mandibular lateral incisors.
3. Second premolar or molar extraction rarely is satisfactory because it does not
provide enough space near crowded anterior teeth or options to correct midline
discrepancies

7. Incisors
• Extraction of a lower incisor tends to result in lingual tilting of the
remaining lower labial segment teeth and a reduction in intercanine
width, which will produce an increase in overbite and often an increase in
crowding, particularly in a growing child.
• Occasionally, if the lower canines are distally inclined and the lower labial
segment crowded in a child who refuses fixed appliance treatment, an
acceptable compromise can be reached by extraction of one or two lower
incisors. If a lower incisor is excluded from the arch, its extraction may
result in satisfactory alignment, but often a sectional lower fixed appliance
is indicated to achieve good root paralleling.
• Upper incisors are rarely the teeth of choice for extraction, but where
trauma or morphology have reduced their prognosis, or an incisor is
grossly displaced, there may be no alternative.

9. Canines
• Because of their position as the cornerstone of the arch, canines are
usually only considered for extraction if they are:
• severely displaced and/or crowded out of the arch. Occasionally, in cases
with severe crowding, the first premolar erupts into contact with the
lateral incisor. This can be aesthetically acceptable ,which is a great bonus,
particularly in the upper arch, as the canine is broader than the first
premolar and extraction of the latter alone would not provide sufficient
space for alignment of the former.
• However, the occlusion should be checked to ensure that no displacing
contacts are present on lateral excursions. Otherwise, fixed appliance
therapy is usually required following removal of a canine to achieve a
satisfactory contact between the lateral incisor and the first premolar.

11. A B
(a)Result following removal of displaced lower
canine
(b)patient who had both upper palatally
displaced canines extracted.

12. First premolars
• First premolars are the teeth of choice for relief of moderate to severe crowding in
either arch.
• By virtue of their position within the arch, extraction of the first premolars
provides space for alignment and retraction of the labial segments, as well as relief
of buccal segment crowding.
• Extraction of a first premolar in either arch usually gives the best chance of
spontaneous occurrence of acceptable alignment.Also, if space closure is
complete, a good contact between the canine and first premolar can often be
achieved. This is of particular value in the lower arch where, provided that the
canine is mesially inclined, spontaneous alignment of the lower labial segment
may occur. This is most rapid within the initial 6 months following extraction.
• If the canines are distally inclined, they will not upright spontaneously into the
extraction space and fixed appliances will be required for their retraction.

13. (a)–(c) Class I malocclusion with moderate upper and
lower crowding, treated by extraction of all four first
premolars; (d)–(f) occlusion a year after extractions.
A
B
C
D
E
F

15. First premolars
• In the upper arch the first premolars usually erupt prior to the
maxillary canine and maximum spontaneous improvement in the
position of this tooth can be achieved if the first premolar is
extracted just before its emergence. However, if space is at a
premium, a space maintainer should be fitted first.
• If the crowding is mild, extraction of first premolars may result in
residual spacing. If fixed appliances are then used to close the
remaining space, there is a danger of over-retracting the labial
segments, which may have deleterious effects upon the profile. In
cases with mild crowding, consideration should be given to
extracting teeth further distal in the arch

16. Residual spacing in a
patient with mild
crowding who had all
four first premolars
removed

18. Second premolars
• The indications for extraction of second premolars include the
following:
1. congenital absence of the second premolars and crowding of the
arch;
2. hypoplasia of the second premolars and crowding of the arch;
3. severe displacement of the second premolar;
4. mild to moderate crowding (2–4 mm per quadrant);
5. where space closure by forward movement of the molars rather
than retraction of the labial segments is indicated.

19. Second premolars
• Extraction of the second premolars is preferable to
extraction of the first premolars in cases with mild to
moderate crowding as their extraction alters the
anchorage balance, favouring space closure by forward
movement of the molars.
• In order to facilitate this and to ensure a satisfactory
contact between the first premolar and the first molar,
fixed appliances are required, particularly in the lower
arch.

20. First permanent molars
• First permanent molars are never an
orthodontist's first choice. However, their
extraction may be indicated if their prognosis
is compromised to such an extent that they
are unlikely to last for a reasonable time.

21. Second permanent molars
• Indications for extraction of second permanent molars include the following:
1. facilitation of distal movement of the upper buccal segments;
2. relief of mild lower premolar crowding;
3. provision of additional space for the third permanent molars and thus reduction
of the likelihood of their impaction;
4. prevention of lower labial segment crowding.
• Because of the greater tendency for mesial drift in the upper arch, extraction of
second permanent molars will not provide space for the relief of premolar or labial
segment crowding without using appliances

22. Extraction of second molars allowed
spontaneous relief of anterior
crowding, with early eruption of the
third molars

23. Third permanent molars
• Early extraction of these teeth has been advocated in
the past to prevent lower labial segment crowding.
However, most oral surgeons are now unwilling to
remove symptomless wisdom teeth. Research into the
role of the third permanent molar in lower labial
segment crowding has not demonstrated a clear-cut
case of cause and effect. Studies have shown that
patients with absent third molars are less likely to
exhibit crowding, but are also likely to have smaller
teeth than average.

24. Serial extractions
Serial extractions were introduced in the 1940s to treat Class I malocclusion complicated by severe
labial segment crowding. The aim was to spontaneously guide the developing dentition into good
alignment without the use of appliance treatment by selectively timing deciduous and permanent tooth
extractions.
The disadvantages of the procedure include:
• Extractions may require multiple procedures under general anaesthesia and are a stressful experience
for the patient.
• Early loss of the first deciduous molar may result in mesial drift of the buccal segments with further
space loss.
• The lower canine may still erupt into the first deciduous molar space before the first premolar
resulting in first premolar impaction.
• There is no spontaneous correction of an incorrect incisor relation-ship, hence it is only useful in Class
I cases.
• There is a risk of lower incisor retroclination and deepening of the overbite.
• Patients may still require later appliance treatment.
Serial extraction is rarely undertaken in its classically described form because of the disadvantages
stated above and the current wide availability of fixed appliances. Occasionally, a modified version of
the procedure may be carried out (e.g. extraction of deciduous canines to allow alignment of the
incisors or for interceptive treatment of palatal maxillary canines) to simplify later appliance treatment.

26. • Balancing extraction:Extraction of a
contralateral tooth during the mixed dentition to
minimise a shift of the dental centreline
• Compensating extraction:Extraction of an
opposing tooth during the mixed dentition to
prevent its over-eruption and to maintain
occlusal relationships between the arches